This invention relates, in general, to semiconductor devices, and more particularly, to a method of fabricating micromechanical devices.
Micromechanical devices are used for a wide range of applications. These devices or micro-switches have the advantage of providing superior switching characteristics over a wide range of frequencies. One type of micromechanical switch structure utilizes a cantilever beam design. A cantilever beam with contact metal thereon rests above an input signal line and an output signal line. During switch operation, the beam is electrostatically actuated by applying voltage to an electrode below the cantilever beam. Electrostatic force pulls the cantilever beam toward the input signal line and the output signal line, thus creating a conduction path between the input line and the output line through the metal contact on the cantilever beam.
In fabricating this type of micro-switch, manufacturing nonuniformity can result in poor metal step coverage of the contact metal. Poor metal step coverage results in micromechanical devices having decreased reliability and performance. If the step coverage is poor enough, voids in the contact metal can cause problems with the formation of the conduction path described above.
In view of the foregoing discussion, it would be advantageous to have a more manufacturable process for making electromechanical devices. Accordingly, there is a need for a micromechanical device with reliable mechanical and electrical contact characteristics.